In the low pressure turbine of a gas turbine, in particular for an engine for aeronautic applications, acoustic emissions are generally reduced by appropriately selecting the number of aerodynamic profiles, i.e. the airfoil count.
The airfoil count is chosen so as to obtain sound waves of gradually reduced amplitude as they propagate inside the turbine, by virtue of the acoustic interactions between rotor arrays and stator arrays, thus obtaining relatively modest acoustic levels at the aeronautic engine exhaust.
This noise control solution has the disadvantage of imposing the number of airfoils and thus of limiting freedom of action in design with regards to aerodynamic optimization.
A different strategy for reducing acoustic emissions consists in adding noise attenuation devices of the passive or active type, within the aeronautic engine. In particular, the passive type devices are defined by soundproofing panels comprising resonators which are appropriately designed to reduce the amplitude of the acoustic emissions. In the known solutions, such panels are applied to the surfaces of the exhaust cone of the gas turbine, downstream of the low pressure turbine, typically at the inner ring of the exhaust cone.
Such a solution has the drawback of having a rather low noise deadening efficacy because of the small available space for arranging the soundproofing panels.
The need is thus felt for a different solution which allows to improve the noise deadening at the low pressure turbine outlet.
Document U.S. Pat. No. 3,802,187A, which corresponds to the preamble of claim 1, suggests to add a splitter in each space between the blades of the last stator array, so as to split in radial manner such a space into an inner conduit and an outer conduit. This document, however, provides no indication on acoustic emissions nor on a possible reduction thereof.